UNIVERSITY OF ILLINOIS

Agricultural Experiment Station

BULLETIN No. 314

A TECHNICAL STUDY

OF THE MAINTENANCE AND

FATTENING OF LAMBS

AND THEIR UTILIZATION OF A RATION OF ALFALFA HAY AND CORN

BY H. H. MITCHELL, W. G. KAMMLADE, AND T. S. HAMILTON

URBAXA, ILLINOIS, AUGUST, 1928

CONTENTS

PACE

PLAN OF THE EXPERIMENT 31

CHEMICAL COMPOSITION OF CHECK LAMBS 33

MAINTENANCE EXPERIMENT 37

Body Weight Changes 38

Results of Digestion and Metabolism Trials 38

Average Daily Intake of Feed and Energy 40

Composition of the Maintenance Lambs 40

Changes in Energy Content of the Maintenance Lambs 44

Corrected Maintenance Requirements 45

Net Energy Required for Maintenance 47

THE FATTENING EXPERIMENT 48

Results of the Digestion and Metabolism Trials 50

Composition of the Fat Lambs 51

Composition of the Gains in Weight 54

Distribution of Added Nutrients in the Carcasses 56

Utilization of Feed Energy in Fattening 57

SUMMARY 59

A TECHNICAL STUDY OF THE MAINTENANCE

AND FATTENING OF LAMBS AND THEIR

UTILIZATION OF A RATION OF

ALFALFA HAY AND CORN

H. H. MITCHELL, W. G. KAMMLADE, AND T. S. HAMILTON1

The lack of information concerning the nutrient requirements of sheep and their efficiency in utilizing food nutrients, is mainly responsi- ble for the general application to sheep of results obtained with cattle, and for the complacency felt in thus transferring bodily to one species information and measurements secured with another. It is high time that experimental investigations on the nutrition of sheep be carried out that will either establish this assumed similarity between sheep and cattle or will permit a separate evaluation of sheep.

In Bulletin 283 of this Station is a description of an experiment on 12 sheep designed to determine the maintenance requirement in terms of metabolizable energy, the composition of gains put on during fattening, and the relation between the metabolizable energy consumed above maintenance and the gross energy of the gains made. The ra- tions used in all cases consisted of alfalfa hay only. The rate of fat- tening secured on alfalfa hay alone was slow, and the refusal of feed in some of the metabolism trials as well as during the fattening period complicated the interpretation of some of the results secured. It was therefore decided to repeat the experiment using a ration more accept- able to sheep and more conducive to fattening. In other respects also the plan of the second experiment differed from that of the first tho the objects sought were essentially the same.

PLAN OF THE EXPERIMENT

The general plan of the experiment provided for the slaughter and analysis of a group of check lambs at the beginning of the experiment and of a group of fattened lambs at the end of the experiment. From these results the composition of the gains put on during fattening could be computed. A third group of lambs was to be fed such amounts of the fattening ration as may be required for the maintenance of weight, The slaughter and analysis of these lambs at the end of their mainten- ance feeding either would demonstrate that the ration consumed was in fact a maintenance ration (with respect to energy) or would afford

'H. H. Mitchell, Chief in Animal Nutrition; W. G. Kammlade, Assistant Chief in Sheep Husbandry ; and T. S. Hamilton, Associate in Animal Nutrition.

31

32 BULLETIN No. 314 [August,

a more or less satisfactory' basis for correcting the ration fed by mak- ing due allowance for energy stored in or lost from the body during the feeding period.

It was decided to use young lambs in this work and to carry the fattened lambs to a desirable market weight of approximately 90 pounds. In the spring of 1925 the required number of grade lambs, about three months of age was available, and accordingly on April 16 six of these lambs were killed and subsequently analyzed. These were to constitute the check group. The ration chosen consisted of equal parts of alfalfa hay and corn. Two other groups of lambs were started on maintenance and fattening rations, but they did not eat well. They did not adapt themselves to the system of individual feeding, probably because they were too young, and the experiment was therefore dis- continued.

In the fall of the same year some lambs were obtained from an Oregon ranch. They were a mixed group of ewes and wethers, dropped by western ewes bred to purebred Hampshire rams. At the time the experiment was resumed in September, they were from five to five and a half months old. On September 21, eight of these lambs were slaugh- tered and analyzed as a check group; another group of eight was fed a ration of alfalfa hay and corn in equal parts for maintenance of weight, while a third group of nine was fed for fattening on the same ration. The lambs were fed individually in all cases.

The individual feeding of these lambs was successful. The main- tenance group was on feed until the early part of February or March, the final date varying for different individuals. During this period metabolism and digestion trials were made upon each of the eight lambs. At the termination of the period of experimental feeding, the lambs were slaughtered and analyzed.

The lambs in the fattening group were fed until weights approxi- mating 90 pounds were reached, when they were slaughtered and ana- lyzed. Two of the lambs were slaughtered on December 21, 1925, five on January 5, 1926, one on February 9, and one on February 18. Di- gestion and metabolism trials were made upon only five of the nine lambs in this group.

The pen in which the lambs were allowed to exercise was approxi- mately one by five rods. The lambs were fed in individual feeding crates located in a shed open toward the south. Water and salt were provided ad libitum. Except at feeding time, the lambs were allowed the run of the open pen. Body weights were taken weekly, and all feed used was sampled continuously and submitted to a routine chem- ical analysis, including the determination of calcium and of the heat of combustion. The carcass samples also were analyzed for calcium and gross energy.

THE MAINTENANCE AND FATTENING OF LAMBS 33

CHEMICAL COMPOSITION OF CHECK LAMBS

Altho the results of the analysis of the first group of check lambs were not used in the later computations of the experiment, they are nevertheless reported because of their interest and importance as rep- resentative of the composition of lambs three to four months of age.

Two samples were prepared from each lamb for chemical analysis: ll) a carcass sample prepared from one-half of the dressed carcass, including one kidney; and (2) an offal sample, including the blood, head, skin, and feet, visceral fats, and all viscera except the kidneys. A composite wool sample for the group of six lambs was also analyzed, the lambs being shorn before slaughter. In preparing the two samples the different tissues were ground separately according to convenience and ultimately mixed together thoroly.

The slaughter data, the total weights of lean, fat, bone, offal, and wool, and the percentage composition of the chemical samples from the first group of grade lambs will be found in Tables 1, 2, and 3. The estimated percentage composition and gross energy content of the lambs, on the basis of the live weight as well as of the empty weight, are given in Table 4.

About a year before the first group of check lambs was slaugh- tered, advantage was taken of an opportunity to analyze a number of new-born lambs that had died from unknown causes a day or two after birth. Four of these new-born lambs were of average weight or better and appeared normal in every respect. The first two were pre- mature, having been dropped about ten days before the termination of the normal gestation period. They were subnormal in weight and composition. Since these analyses have not heretofore been published, they have been summarized in Table 5. They possess the same gen- eral significance as the analysis of other groups of lambs reported in this bulletin.

The second group of check lambs, used in the computations of this experiment, was slaughtered and analyzed according to the same scheme as the first group, the samples being composited in exactly the same manner. The results obtained are summarized in Tables 6. 7, 8. and 9.

These western lambs were in somewhat poorer condition than the younger grade lambs killed in the spring of 1925. Another noticeable difference between the western and the grade lambs relates to the ash content. The western lambs contained 4.79 percent of ash on the basis of the empty weight, while the grades contained only 3.32 percent. The calcium made up approximately the same percentage of the total ash in each group, i.e., 28.5 and 27.4. The greater ash content of the west- ern lambs may be traced definitely to their greater bone content. No weights on the total skeleton are available, but the bones in the dressed

34

BULLETIN No. 314

[August,

TABLE 1. — SLAUGHTER DATA FROM FIRST GROUP OF CHECK LAMBS

(All weights in pounds)

Lamb No	1	21	25	12	22	30	Average
Live weight	47.4	50.1	47.8	54.4	50.9	49.7	50.1
Wool	1.76	1.65	1.08	1.71	1.54	1.11	1.48
Blood ...	1.94	2.19	2.25	2.19	2.31	2.38	2.21
Skin and feet	4.44	4.56	4.56	4.38	5.13	4.69	4.63
Caul fat	.56	.56	.50	.56	.19	.44	47
Gut fat	.31	.31	.44	.56	.75	.44	.47
Contents of first three	6.25	4.63	6.38	6.06	4.31	4.69	5.39
Contents of 4th stomach	2.44	2.06	2.13	1.38	1.75	1.31	1.85
Contents of entire	8.69	6 69	8 51	7.44	6.06	6.00	7.23
Warm dressed carcass. . . Cold dressed carcass	20.81 20.05 3.65	25.38 24.85 2 09	21.06 20.90 76	27.31 26.53 2 86	24.50 23.50 4.08	24.25 23.50 3.09	23.89 23.22 2.76
	18.3	13.3	17.8	13.6	11.9	12.1	14.5
Dressing percentage	42.7	49.6	43.8	48.8	46.2	47.2	46.4

TABLE 2. — WEIGHTS OF SAMPLES ANALYZED FROM FIRST GROUP OF CHECK LAMBS

Lamb No.	Empty weight	Dressed carcass composite	Offal	Wool
Lean	Fat	Bone	Total
1	kgs. 17.58 19.69 17.81 21.30 20.35 19.84 19.43	grams 5 988 7 352 6 035 7 672 6 876 6 748 6 779	grams 1 391 2 035 1 432 2 286 1 706 2 Oil 1 810	grams 1 736 1 722 1 783 1 998 2 028 1 808 1 846	grams 9 115 11 109 9 250 11 956 10 610 10 567 10 435	grams 6 740 6 730 7 140 7 161 7 561 7 224 7 093	grams 798 748 490 776 699 503 669
21
25
12
22
30
Average.. .

TABLE 3. — PERCENTAGE COMPOSITION AND ENERGY VALUE OF SAMPLES ANALYZED FROM FIRST GROUP OF CHECK LAMBS

Lamb No.

Dry substance

Crude protein

Ether extract

Ash

Calcium

Calcium in percent of total ash

Gross energy per grams

Carcass composite samples

1	44.04	17.11	21.23	5.21	1.85	35.5	sm. cals. 2 866
21	48.32	16.32	24 77	4 62	1 46	31.6	3 088
25	43.47	18.26	19 62	5 22	1.72	33.0	2 746
12	53.56	15 95	26 74	3 55	99	27.9	3 306
22	44.02	16.87	22 15	3 90	1.28	32.8	2 897
30	44 74	16 46	23 32	3 55	1 01	28 5	2 951
Average. . . .	46.36	16.83	22.97	4.34	1.39	31.6	2 976

Offal samples

1...	32 . 08	16 89	12 10	2 47	59	23 9	1 969
21	34.31	16.88	12 79	1 85	47	25 4	2 086
25	29.76	17 07	9 93	2 10	48	22 9	1 780
12	32.70	16 06	12 22	1 83	40	21 9	2 112
22 .	28.93	16 37	0 52	1 89	39	20 6	1 760
30	28.94	16 44	9 58	1 94	41	21.1	1 743
Average	31.12	16.62	11.02	2.01	.46	23.5	1 908

Composite wool samples

1-30... 91.89

70.75

13.75

7 47

.28

3.75

4 938

1928]

THE MAINTENANCE AND FATTENING OF LAMBS

35

TABLE 4. — PERCENTAGE COMPOSITION AND GROSS ENERGY CONTENT OF FIRST GROUP OF CHECK LAMBS

Lamb No.

Dry substance

Crude protein

Crude fat

Ash

Calcium

Calcium in percent of total ash

Gross energy per gram

On basis of live weight

1	32 11	15 15	13 29	3 25	98		sm. cals. 2 013
21	36 80	15 32	16 37	3 08	86		2 290
25	30.46	15.00	11.95	3.09	. 90		1 870
12	38 33	14 63	16 94	2 47	80		2 370
22	32 47	15 24	13 72	2 64	72		2 059
30	32.27	14.. 54	14.32	2 44	.61		2 050
Average. . . .	33.74	14.98	14.43	2.83	.78		2 109

On basis of empty weight

1. ..	39 30	IS 54	16 27	3 98	1 20	30 2	2 465
21	42.46	17.67	18.82	3.56	1.00	28 1	2 643
25	37 06	IS 25	14 54	3 76	1 09	29 0	2 276
12	44.41	16 95	19 63	2 SB	70	24.5	2 746
22	36.86	17.30	15 58	3.00	,82	27.3	2 338
30	36 69	16 53	16 28	2 77	70	25 3	2 331
Average. . . .	39.46	17.54	16.85	3.32	.92	27.4	2 467

TABLE 5. — PERCENTAGE COMPOSITION AND GROSS ENERGY OF XEW-BORN LAMBS

Breeding	Birth weight l	Dry substance	Crude protein	Ether extract	Ash	Gross energy per grams
	Ibs. 6 0	18 99	11 38	2 32	2 35	sm. cals. 1 Oil
	7 0	18 04	11 19	1 SI	•' (is	882
	9 75	23 02	14 94	2 S2	3 36	1 148
	10 7	23 32	15 44	2 SS	3 02	1 30S
Southdown	6 6	24 69	15 19	2 76	3 S4	1 324
Southdown	7.2	22 66	16 44	2 44	3.35	1 236
Average2		23.42	15.50	2.72	3.39	1 254

'Sixteen Southdown lambs dropped from ewes in the University flock during the same year averaged 7.7 pounds in weight at birth; 24 Rambouillet lambs averaged 9.7 pounds. Exclusive of first two lambs.

TABLE 6. — SLAUGHTER DATA FROM SECOND GROUP OF CHECK LAMBS

(All weights in pounds)

Lamb Xo	156	29	64	44	83	7>	80	81	Aver-
									age
Live weight	59 7	60 6		5s 4	60 6	57 4	5S 1	•	58 6
Wool	3 38	3 38	2 81	3 06	3 69	•' ti3	3 13	3 13	3 15
Blood	3 44	2 81	2 63	2 25	2 7.")	3 00	2 r:>	2 63	2 7s
Skin and feet	6 38	4 75	5 38	4 SI	5 (ID	-	5 19	5.38	5.34
Caul fat .	25	69	3s	81	44	."id	56	38	.50
Gut fat	56	44	56	50	44	44	44	44	.48
Contents of first tin	5 19	6 81	4 81	5 31	9 81	6 56	6 06	5.69	6.28
Contents of 4th stomach	4 31	3 13	3 06	2 50	3 56	2 88	2 69	2 44	3.07
Contents of entire alimentary tract Warm dressed carcass. . Cold dressed carcass .... Percent shrinkage Percent "fill"	9.50 26.19 25.61 2.21 15 9	9.94 28.19 27.60 2.09 16 4	7.87 27.94 27.20 2.65 13 7	7.81 27.56 26.86 2.64 13 3	13.37 26.25 25.49 2.90 22 1	9.44 26.38 25.68 2 ..65 16 4	8.75 27 . :>!> 26.66 3.27 15 1	8.13 8 ! 3.28 14.6	9.35 26.99 26.27 2.70 15.9
Dressing percentage. . . .	42.9	45.6	47.3	46.0	42.1	44.8	45.9	44.9

36

BULLETIN Xo. 314

I

ss .i;ed 1.846 grams for the grades and 2.588 grams for the

western lambs, which is equal to 9.52 and 11.61 percent respectively the empty weight and 11.45 and 13.52 percent of the fat-free empty weight.

TABLE 7. — WEIGHTS OF SAMPLES ANALYZED FROM SECOND GROUP OF CHECK LAMBS

Lamb ;•.	Empty	Dressed - •- - •	-'•	Wool
:.'.	Fat	Bone1	!' •'
ii	1 22 -- 22. 97 22 : 22 7 21.41 21.75 22.4 21. ( 22.30	- ' 413 1 •-; . . ,- ] L7 - B •- • ' r 896 : _ K ' 616	- : 92 1 441 ' ". 1 133 1 130 1 211 1 000 1 349	• - 858 2 • • . 2 641 2 523 2 < 2 646 2 543 . 588	11 453 12 047 9 ' 78 I 11 3.50 • 2 • 11 7i 10 342 11 553	- - 852 - 7 571 " 617 7 ;- 7 • 7 - 7 886 - . '	1 .533 1 533 1 27i ; 388 1 674 1 193 1 420 1 • -• 1 430
• .
44
S3 ... .
--
-
51
' : - ...-

Exclus f I ies of 1 I and feel

TABLE S. — PERCENTAGE C< - fa < ION AND ENERGY VALUE OF SAMPLES ANALYZED FROM SECOND GROUP OF CHECK LAMBS

Lamb ,	-	pro-	: • - -		Calcium	in percent • .	C per trr
•mposite san.:
156.. .. •	' - • - Z - - - ti .. •	17 17 1 7 17.31 - - - • • - ~	; _ - - - - - • • - 7 - 7 1 -	- ; ' 1 ! 4.77 - •- 5.90 5.90	.- ' 1 - • _ 1.56 _ • •_ 1.99	1 ~ 1 2 34.4 - J • - • 3.3 . 7	caii. 2 - ' - _ ^ - 177 ^ 2 691
\
-
•
•
Offal samples
156	27 7 i i 30.26	- - • - 16.44	7.32 12.63 13.15 9.60 11.14 9.91 10.36	i ii • ii .	.71 _ 88 77 - .71	K 23.1 . ! 2 24.6 - 25.0 24.5	J7 2 005 1 701 2 - 1 77- 1 914 1 71- •
.
- - 78
- -
Composite wool sample
Entire group	91.57	70.19	6.47	10.88	.28	2.57	4 563

: -

THE MAINTENANCE AND FATTE>

-

TABLE 9. — PERCENTAGE COMPOSITION AND Gr;< .•-- I : NTENT

OF SECOND GROCP OF CHECK LAMBS

Lamb Dry Crude : Xo. substance pr- . • :ract	Ui		- - • ri	Gross '- • sram
1 . M • . reigfat
156 . 31 66	16.66 16.42 12 12 • - 13.04 LS.84 14.75 16 . 02 10.95 11.37 17.06 11.41 16.96 16.40 11.90	4.73 32 3.45 4.34 3.49 ; 21 ; 3.99 - 2	1.32 1 . _ _ 2 - .01 1.14	', ','.', .' ','•', / i - o; *. to	co2s. i • \ . 17 - - • I 851 1 909 1 : a •- 1 171
29 ... 34 73
64 33.74
44 35 OS
83 . 30 9>,
78 ... . 32 54
80 ?.3 33
81 . •••-•,
Average 33.09
• _ . | • - • - gfai
156 37.64	19.81 11.51 19.64 L8.7S 15.10 18 . 29 L7 . 02 14.11 19.17 13.61 20.09 13.44 1 -• _ • 19.52 14.15	! • - 1 S7 1 ' 1 18 ' - 9S 1 - - 4.79	: ^ - 1.45 >7 1.43 3 18 1.36		2 1 1 2 V ' _ ' 2 581 . -' _ 284 2 274 2 2li 2 346
29 41.54
64 39 09
44. 10.49
83 "
78.. 5.8J
39 24
81 S.24
Average 39.37

MAINTENANCE EXPERIMENT

The feeding of the eight maintenance lambs started on October 10. 1925. Their weekly weight.- from this ".mil February 6 or 13

are given in Table 10.

TABLE 10. — WEEKLY WEIGHTS OF LAMBS DURING MAINTENANCE FEEDING PERIOD*

- ' : ~

Lamb Xo	10	11			-	.	-	136
				_
Oct. 10	65	63	65	•	-	63	i
17	.	-		'	i	61	61
24		]	j	66	65		-
31	64	65	65	fifi	65	_
Nov. 7	72	69	'	69	1		-	J
14		-	69		66	64	-
21	69	~	71	~	69
28	67	-	70	69		66		64
Dec. 5	-	66	J	71	1	i	69
12		1	J	'	-	-
19	66	65	•	a	66			66
-	-	69	-	-_	71	•	n	-
Jan -	'	70	73	i	74	70	73
9	70	-	n		-		j |	69
16	69	71	--	j	-I	-		-
23	71	74	-	74		73		-
30	71	73		J	'	73		-
Feb. 6	73	79	77	::		n	1	- .
13		76			-'
Final weight ....	69.4	73.2	71.7	71.6	74.9	69.0	n i	'- -
Average weight .	68.2	69.2	70.6	J	69.3	67.1	70.6	66.5

'Xo. 136 was slaughtered on Fei>: . • -. » N : - : . . . " - » and

Xos. 11 and 43 on March 4. Some of the weekly w, j ;1 from

the table and from the averages because of irregularities incide:.'

38 BULLETIN Xo. 314 [August,

Body Weight Changes

The weight records in Table 10 indicate that the feeding was ap- preciably more liberal than a maintenance ration. All lambs increased in weight slowly. They were started on .8 pound of alfalfa hay and .8 pound of corn per head daily. On November 21 this allowance was decreased to .7 pound of each feed daily for all of the lambs except Nos. 75 and 136. The same reduction was made for Lamb 75 on No- vember 28; Lamb 136 was carried thruout at the higher level. The chemical composition of the different samples of feeds collected at the sheep barn and at the Nutrition Laboratory, where the metabolism tests were run, is given in Table 11.

Results of Digestion and Metabolism Trials

In the last few weeks of the experiment each of the maintenance lambs was subjected to a digestion and metabolism trial during which feces and urine were quantitatively collected for 10 days. In each case the lambs had been consuming for several weeks prior to the collection period a constant daily amount of feed, the same as that consumed during the time of collection of excreta. The excreta passed during the first day in the metabolism crate were rejected. The meta- bolism crates used have been described in Bulletin 283 from this Sta- tion. The coefficients of digestibility for the different nutrients, com- puted according to the ordinary method, have been summarized in Table 12.

In addition to the routine analyses of feed and feces, the gross energy was also determined in these samples, as well as in the urine, by combustion in the bomb calorimeter. These determinations per- mitted the computation of the metabolizable energy in the mainten- ance rations (Table 13). The nitrogen balances of the lambs during the metabolism trials are shown in Table 14. All lambs were storing nitrogen.

An average of 59.7 percent of the gross energy of the ration was metabolizable. Armsby has computed1 from his own experiments on steers that the gross energy of alfalfa is 44 percent metabolizable and that of corn 75 percent metabolizable. For a ration containing ap- proximately equal amounts of gross energy from these two feeds, as was true of the ration fed the maintenance lambs, one would expect with steers that 59.5 percent (average of 44 and 75) of the gross energy would be metabolizable, a value practically identical with the average percentage actually obtained with the maintenance lambs. Forbes and associates have recently reported2 some energy metabolism studies on two steers receiving a ration containing equal parts of alfalfa

'Arinshy, H. P. Tho nutrition of farm animals, 661. Macmillan. 1917. "Forbes, E. B., ct al. Amer. Soc. Anim. Prod. Proc., 1927.

1928}

THE MAINTENANCE AND FATTENING OF LAMBS

39

	(iross energy per gram		~ c: t- — < i.e rr. £ — S -r J) -r		Z £. 'S '" ~ x ~. 5 c c^	i -C £
	a •~-		~ ' ':£ ' T		x ^* i^- d -o :o	IIIII:K ,>s
03 X	c		s. ! . .			EH
H	•a		-: x r: x -t — 5; — — — X :S		o^re-t-	X •o ri us
NANC			5. r- r- b- -,c ce
\	§1 — i-		i; x cr. ?1 £ £		ce M re s; re	•M IN O
H a	a £		~ ~~		re re re re re	E
£ a	ii		X; "~e CT: f~ r- X		-• — < x -r M M re — x t~	'c 'C
•HV.IS.S.			i 0 •- ~ - -0		7^ 7j re c*i 71!	o
c O Q	r t	> 2		_	re c-i re £. ri	» =
		£	~ -r -r ^r -r re		£SSE2	I
ic O	i = •g'S		^; re c: X ~ 7*		•2S7!qs	i "E
r.	r1" £		i -i i-e -• — re		X C5 ~ c: X	1
i s 0	^ ^					c 1
o o	|		X=!5S3^ =		re t; -r •*? -^
s w H G	"1		SSSSS		x x r^; * x	O ID re
1.
TABLE 1	Description of feed sample		i'i^'C'u		I''ed at barn Metabiilism trial1 . . Metabolism trials2. . Metabolism trials3. . l'Vd at barn	— re t_ — i| H 2~ = n
	o "3 Q		='-? S u ^ "T>I ^ ^ o		L=i! j3 •^ ^ t~ ^ —	'These sai metaboliam trial

40 Buiuocr Na 3M

.-•'--" ~ - " - - - LAMBS

•rita	- ••MM	- proteia	-	Crud« -	- • -
ft		'	!*«*•	fwnri.	-
•		1		-	sa
'			-. •	'	-
			-	-
	"	60
~	"»	-	-		".
-	"
	~	!	gj
-	"	]	53	-	59
- -	"	-	i	-- :	-

gross

maintei cioi • . .' '

- , t. These 1 ~ sely with thos

-

Di:".v Iz:^ke c: Feed and E~ergy

i ring the main1 \ r 100

- ~ ..• • • • .. • _ : " r - i Q to 1

100-: .

. * : to 100 and i ;• :. - ~".~ ::.e ral

-thini: f the weight of i tot two-thirds

100. _ body

=ize with i :o i - tsm v the 1 met

- - _

mus - . - . • . _ • . • . . _ - - 2 st g

horizontally Since :he — A.r.-enanre of these lambs involved both the

.

- is th< " :

T . _ " ould be

eriod - •. - •

kings e ob-

tained only by «; v;^r.:ering and analyzing the maintenance lambs and comparing '.heir : r.'.-rr.: o: energy with that of the check lambs, which

, - . - .

\

Composition of the Maintenance Lambs

iin- tenance lan'r - ir- given in Tables 16. 17. 18. and 19. "With this group

-

-.

*—— - •----.'--• -_;-£ r : - ~ •? '_ ^ _: •: - ;

Jt

-.- - - ------ Z ••—. —

— ^ - - - r - - : 5 — s

5.. 5 = .-------•;

.- 5 1 = •£--.-.-.--.-.- -

. - ^ . _. . _ . _ _

— -- " -

s

z =

"

z

- • - ~ ~ _ 2

: r " C I " • — 3

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42

BULLETIN No. 314

[August,

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1928]

THE MAINTENANCE AND FATTENING OF LAMBS

43

TABLE 16. — SLAUGHTER DATA FROM THE MAINTENANCE LAMBS

(All weights in pounds)

	136	85	75	22	10	25	11	43	Aver-
									age
Live weight	72.8	72.4	69.0	71.7	69.4	71.6	73.2	74 9	71 9
Wool	2 80	4 00	3 90	5 25	4 50	6 65	4 75	4 91	4 60
Blood	2.80	3.25	4.10	3.70	2.90	3.20	3 00	3 17	3 27
	8 50	7 20	5 70	6 50	5 15	6 35	6 66	6 83	6 61
Caul fat. .	.80	1.60	1.50	1 55	1 35	1 75	1 69	1 46	1 46
Gut fat	.80	1.10	1.35	1.25	1.40	1.10	1 24	1 02	1 16
Contents of first three	5.15	5 15	4.70	5 40	3 65	5 05	5 29	5 45	4 98.
Contents of 4th stomach	3 90	2 55	3 05	2 55	2 00	2 15	3 07	3 40	2 8$
Contents of entire alimentary tract Warm dressed carcass. . Cold dressed carcass .... Percent shrinkage	9.05 37.00 36.08 2.49	7.70 37.50 36.90 1.60	7.75 35.50 34.60 2.54	7.95 35.75 34.86 2.49	5.65 39.50 38.91 1.49	7.20 37.25 36.55 1.88	8.36 36.75 35.03 4.68	8.85 37.75 36.86 2.36	7.81 37.1$ 36.22 2.44
Percent "fill"	12 4	10 6	11 2	11 1	8 1	10 1	11 4	11 8	10 8
Dressing percentage. . . .	49.5	51.0	50.2	48.6	56.1	51.1	47.8	49.2	50.4

TABLE 17. — WEIGHTS OF SAMPLES ANALYZED FROM THE MAINTENANCE LAMBS

Lamb	Empty		Edible flesh			Offal	Wnnl
No.	weight	Lean	Fat	Total
136.. .	kgs. 28.94	grams 10 767	grams 2 614	grams 13 381	grams 3 998	grams 8 838	grams 1 270
85	29 34	9 989	2 960	12 949	3 970	8 155	1 814
75.	27 76	10 677	1 740	12 417	• 4 178	8 672	1 769
22... . 10... . 25... . 11... . 43... . Average..	28 . 94 28.91 29.21 29.43 29.96 29.08	10 427 10 399 10 136 9 59S 9 944 10 242	2 125 4 051 3 304 3 262 3 462 2 940	12 552 14 450 13 440 12 860 13 406 13 182	4 116 3 529 3 791 4 248 4 311 4 018	8 915 7 725 8 530 8 528 8 610 8 497	2 381 2 041 3 016 2 155 2 227 2 084

three instead of two samples were taken from each carcass besides the composite wool sample for the group. The sample of edible flesh represented the lean, including the kidneys, and the fat from the dressed carcass. The bone sample included the bones of the dressed carcass and the bones of the head and feet, as roughly cleaned with a butcher knife. The offal sample contained the blood, the shorn skin, and the flesh, brain, and eyes from the head, together with all viscera and visceral fat.

It is evident from Tables 9 and 19 that the carcasses of the main- tenance lambs were appreciably fatter than those of the check lambs. On the live-weight basis the maintenance lambs contained 19.25 per- cent of fat as compared with 11.90 percent for the check lambs; on the basis of the empty weight these percentages were 21.57 and 14.15 respectively. The increase in weight of the maintenance lambs thru- out their feeding period increased still further the storage of energy in their bodies. Evidently the ration fed was appreciably greater in energy value than the lambs required for the maintenance of energy equilibrium. An attempt to correct the ration fed to energy equili- brium has been made in Table 20.

44

BULLETIN No. 314

[August,

TABLE 18. — PERCENTAGE COMPOSITION AND ENERGY VALUE OF SAMPLES ANALYZED FROM THE MAINTENANCE LAMBS

Lamb No.

Dry substance

Crude protein

Ether extract

Ash

Calcium

Calcium in percent of total ash

Gross energy per gram

Edible flesh samples

136...	49 53	15 38	26 68	.91	.025	2.75	sm. cals. 3374
85	49.49	15.13	27.83	.82	.027	3.29	3612
75 .	41 32	16 63	21 91	89	026	2 92	3033
22	39 61	16 56	22 57	.87	.027	3. 10	3066
10	47.36	14.88	32.03	.77	.025	3.25	3777
25. .	45 47	15 38	30 31	.79	.030	3.80	3706
11	49 04	15 00	32.81	.76	.026	3.42	3820
43.	49 24	15 31	28 63	83	023	2 77	3551
Average. . . .	46.38	15.53	27.85	.83	.026	3.16	3492

Bone samples

136	60.79 59.90 58.66 58.24 57 . 84 60.40 55.74 57.74 58.66	19.17 19.52 19.51 19.38 18.96 19.38 18.02 19.31 19.16 -	17.96 19.77 18.44 17.31 16.71 20.86 19.77 18.59 18.68	20.90 18.78 18.64 18.73 19.55 18.21 16.41 18.35 18.70	7.84 7.09 7.03 7.00 7.33 6.72 6.14 6.99 7.02	37 . 5 37.8 37.7 37.4 37.5 36.9 37.4 38.1 37. 5	2862 3115 2905 2781 2679 3092 2816 2802 2882
85
75
22.
10
25
11. ..
43
Average. . . .
Offal samples
136	31.89 35.99 36.53 35.99 43.01 38.94 39.08 36. 3S 37.23	15.2.5 15.25 13.19 13.81 14.38 14.56 13.94 15.00 14.42	15.51 18.43 21.04 18.74 21.50 20.51 21.21 18.04 19.37	.91 1.09 .97 1.09 .99 .94 .98 1.05 1.00	.026 .030 .035 .023 .034 .026 .022 .029 .028	2.86 2.75 3.61 2.11 3.43 2.77 2.24 2.76 2.82	2319 2650 2674 2639 2914 2889 2811 2524 2678
85..
75
22
10
25
11
43...
1 Average. . . .
Wool samples
136-43	91.57	60.63	8.60	11.6	.177	1.53	4460

Changes in Energy Content of the Maintenance Lambs

The carcasses of the maintenance lambs contained an average of 89.9 therms of gross energy. Assuming that their energy content at the beginning of the feeding period was the same as that of the check lambs at slaughter, i.e., 894 calories per pound, the initial energy con- tent of the maintenance lambs may be estimated; this has been done in Table 20, giving an average estimate of 56.4 therms. Hence during the period of feeding, the maintenance lambs added some 33.5 therms of gross energy to their bodies at the rate of 252 calories per day. The daily ration therefore provided 252 calories of net energy in excess of the maintenance requirements. It may be estimated from Armsby's data1 that the metabolizable energy of a ration consisting of equal

'The average gross energy of the alfalfa hay consumed by the maintenance sheep was 4,108 calories per kilogram and that of the corn, 3.986 calories per

1928}

THE MAINTENANCE AND FATTENING OF LAMBS

45

TABLE 19. — PERCENTAGE COMPOSITION AND GROSS ENERGY CONTENT OF THE MAINTENANCE LAMBS

Lamb No.	Dry substance	Crude protein	Ether extract	Ash	Calcium	Calcium in percent of total ash	Gross energy per gram
On basis of live weight
136...	39.47 41.42 39.55 39.19 44.73 • 44.61 42.07 41.97 41.63	14.96 15.75 16.29 17.05 16.42 18.09 15.62 16.26 16.31	17.46 18.76 17.48 16.65 22.42 21.17 21.23 18.79 J9.25	3.58 3.53 3.77 3.85 3.54 3.78 3.40 3.68 3.64	.97 .88 .97 .92 .85 .82 .81 .91 .88	28.0 24.8 25.5 23.6 23.7 21.5 23.6 24.5 24.4	SOT. cals. 2 504 2 754 2 586 2 583 3 039 3 068 2 849 2 688 2 759
85
75
22 .
10
25
11
43
Average. . . .
On basis of empty weight
136	45.06 46.35 44.56 44.08 48.69 49.59 47.51 47.60 46.68	17.08 17.62 18.36 19.18 17.87 20.11 17.64 18.44 18.29	19.93 20.99 19.70 18.73 24.40 23.53 23.97 21.31 21.57	4.09 3.95 4.25 4.33 3.85 4.20 3.84 4.17 4.09	1.11 .99 1.09 1.03 .93 .91 .92 1.03 1.00		2 859 3 082 2 914 2 905 3 308 3 410 3 217 3 049 3 093
85
75 . ...
22
10
25
11
43
Average. . . .

parts of alfalfa hay and corn is 53 percent net available. Forbes and associates (loc. cit.) have more recently investigated directly the utili- zation of the energy of this ration on two steers. From the data ob- tained it may be computed that the metabolizable energy equivalent to one-half the maintenance requirement of steers, when added to a main- tenance ration, increased the energy balance by an amount equal to 55.4 and 55.7 of the added metabolizable energy. In other words, be- tween a maintenance level of feeding and a level 50 percent higher, the metabolizable energy appeared to have a net availability of a little over 55 percent. This percentage is in close agreement with the value obtained from Armsby's data and has been used in the calculations of Table 20.

Corrected Maintenance Requirements

Assuming, therefore, that the metabolizable energy consumed by these lambs above their maintenance requirements possessed a per-

kilognim. Of the gross energy of alfalfa hay 44 percent is available as metaboliz- able energy, and of corn 75 percent is available (see page 38). Of the metaboliz- able energy in these feeds the percentage available as net energy for fattening is (Armsby, "The Nutrition of Farm Animals,'' page 661) for alfalfa hay 39 percent and for corn 61 percent. Each kilogram of alfalfa hay therefore, contained 4,108 X .44, or 1,808 calories of metabolizable energy, and 1,808 X .39, or 705 calories of net energy: and each kilogram of corn contained 3,986 X .75, or 2.900 calorics of metabolizable energy, and 2,900 X .61, or 1,769 calories of net energy. The aver- age net availability of the metabolizable energy of a ration containing equal parts

705 + 1,769

of these two feeds is therefore

1,808 + 2,900

=52-55

46

BULLETIN Xo. 314

[August.

Average	O OTiS — IS CM T	£0 CM CO to — O T	iverage gross it was found nance lambs, nergy intake, •ed energy.
g	is t- >-* t- ?1 3 30 is CO T t- iS O	cote t~iO iS X x' ft CCO	p had. The •nance sheep y the mainte etabolizable < valent of sto
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CO	CO CO T S: iO 0 — is" O CX IS — TO c; is co r~ T »o uo — iS M T	C1CO C: iO M — — — —CO	• kilogram liv uring the met y. The tola n multiplied gy intake les>
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—	M O — 'O ~ •£ '-; •£ t; '3 ~ '3 — ' *~< i-O CM 1*0	>0 X 0 -H — CO —CO O 'S CO	p at their initi er kilogram of li energy consun lent gives the bolizable energ
	c.	3 : ; a c
O fc .0	Feeding period, days Average body weight, pounds dross energy content, the! ins Final Initial' ( lain Daily intake of metabolizable energy calories2 Daily storage of energy, calories. . . . Assumed availability of metabolizabl energy of the ration, percent Metabolizable energy equivalent of t stored energy,3 calories Maintenance requirements of metalx energy daily, calories	Per bead* J'er 100 pounds live weight: Weight ratio Surface ratio Maintenance requirements of ration,! per 100 pounds live weight: Weight ratio Surface ratio	'Assuming that the niaintenan energy of the check sheep was 1971 ci that an average of 5!).S percent of tl divided by the number of days on 8Daily energy storage divided by . .r>5

192S] THE MAINTENANCE AND FATTENING OF LAMBS 47

centage availability of 55, the daily net energy stored, averaging 252 calories, may be taken as equivalent to 458 calories of metabolizablc energy. The daily intake of metabolizable energy averaged 1,586 calories, so that the maintenance requirement becomes 1,586 — 458 =1,128 calories per head, or 1,637 calories per 100 pounds body weight computed in proportion to weight, or 1,461 calories per 100 pounds computed in proportion to the two-thirds power of the weight (body surface). The quantity of feed has been computed from these values by means of the average metabolizable energy content of the ration (1,074 calories per pound).

The choice between the two estimates of the maintenance require- ment of metabolizable energy is a difficult one, depending as explained above on the proportions of energy used for the basal metabolism and for muscular activity. These are unknown. It would be expected that the more significant method of reducing these estimated require- ments to a body weight of 100 pounds would give the less variable set of values. The standard deviation of the estimates made in accord- ance with the ratio of weights is 226 calories, while that of the esti- mates made in accordance with the ratio of surfaces is 203 calories. However, the coefficients of variation are practically the same, 14.4 and 14.5 percent respectively, so that a choice between the two meth- ods on this basis can hardly be made.

On a ration of alfalfa hay alone it was found in the preceding investigation with older sheep (see Illinois Bulletin 283) , that the main- tenance requirement averaged, for 12 sheep, 1,820 calories of metabo- lizable energy per 100 pounds live weight by using the ratio of weights, and 1,733 calories by using the ratio of surfaces. These figures are ap- preciably higher than those computed in the present experiment, a fact that may reasonably be accounted for by the known poorer utilization of the metabolizable energy of alfalfa hay than of corn.

Net Energy Required for Maintenance

Forbes and associates (loc. cit.) found that the metabolizable en- ergy of a maintenance ration of equal parts of alfalfa hay and corn was 80.8 percent net available for one of their steers (No. 47) and 81.4 percent net available for the other. If lambs may be assumed to be equally efficient in the utilization of the metabolizable energy of a similar maintenance ration, the net energy requirement of the lambs may be computed for "economic maintenance." Applying the average of the two percentages obtained with steers to the average metaboliz- able energy requirements given in Table 20 gives a net energy require- ment of 1,326 calories per 100 pounds live weight according to the ratio of weights and 1,183 calories according to the ratio of surfaces.

Wood and Capstick1 have recently calculated by an indirect matho-

'Wood. T. B., and Capstick. J. W. Jour. Apr. Sci. 16, 325. 1926.

48

BULLETIN Xo. 314

[August,

matical method that a sheep weighing 100 pounds requires daily for maintenance 1.26 pounds of starch equivalent, or 1,348 calories of net energy. This value was computed in proportion to the surface of the sheep and is therefore to be compared with the estimate of 1,183 calories in this experiment. Wood and Capstick obtained their value by a mathematical analysis of data concerning the feed consumption and the variations in weight of twenty-eight sheep. The starch values of the feed consumed were apparently calculated from the average tables of Kellner for fattening steers.

THE FATTENING EXPERIMENT

On September 30, 1925, eight lambs averaging 66 pounds in weight were put upon such amounts of alfalfa hay and corn in equal propor- tions as they would readily clean up. On October 24 a ninth lamb was added to this group. These lambs were slaughtered at approximately 90 pounds in order to determine the nature of the gains made during fattening to a popular slaughter weight and the utilization of the metabolizable energy consumed and used for that purpose. The week- ly weights of these lambs will be found in Table 21. The average daily gains varied from .18 to .36 pound and averaged .25 pound.

The feed consumption of the lambs has been summarized and averaged in Table 22. The feeds fed at the barns were sampled along with the feeds of the maintenance lambs, and the analyses of these samples have been given in Table 11.

TABLE 21. — WEEKLY WEIGHTS OF LAMBS DURING FATTENING PERIOD1

(All weights in pounds)

Lamb Xo	33	69	151	169	67	49	54	90	143
1927
Sept. 30		70	67	69	66	65	66	65	65
Oct. 10		69	69	73	69	55	67	69	66
17		68	71	68	70	55	67	66	66
24	65'	73	71	72	76	61	71	70	07
31	66	72	71	71	73	60	70	70	69
N'ov. 7	71	73	80	72	81	71	76	79	75
14	70	SO	77	78	78	69	78	76	72
21	73	80	78	76	78	69	75	74	73
28	73	85	77	79	80	66	76	77	73
Dec. 5	74	87	7!)	81	83	70	79	82	72
12	80	85	81	84	85	74	84	84	72
19	85	90	88	88	90	77	86	85	73
26	35		86	88		78	89	87	79
1926
Jan. 2	91		90	91		82	92	91	82
9						83			83
16						86			86
23						86			85
30						83			86
Feb. 6						85			90
13						87
17						90
Average weights	75 7	77.7	77 5	77 9	77.4	73 9	76 9	76 8	75 5
Average daily gains. . . . Length of feeding period	.36	.24	.24	.'23	'.29	!l8	27	27	.'l9
in days	73	82	97	97	82	141	97	97	131

'Lambs 67 and 69 were slaughtered on December 21, 1925, after 82 days of feeding; Lambs 151, 169, 54, 33, and 90 were slaughtered on January 5, 1926, after 97 days of feeding; Lamb 143 was killed on February 8, and Lamb 49 on February 18, after 131 and 141 days of feeding, respectively.

1928]

THE MAINTENANCE AND FATTENING OF LAMBS

49

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50

BULLETIN No. 314

[August,

Results of the Digestion and Metabolism Trials

During the period from October 29 to December 5 digestion and metabolism trials were made upon five of the nine fattening sheep. As with the maintenance lambs, the collection periods were of 10 days duration. For two of the lambs (Nos. 69 and 169) no change in feed had been made for 29 days before the collection period. For Lamb 33 the feed had been constant for nine days preceding the digestion experiment, while for Lambs 67 and 151, it had been raised from 2.0 to 2.4 pounds daily on the second day preceding the collection period. The latter two lambs should not have been put on a digestion exper- iment so soon after a change of feed, but nevertheless the results ob- tained in these cases agreed well with the results obtained upon the other lambs. Except on the final day of collection with Lamb 67, there was no refused feed in these digestion experiments.

The chemical composition of samples of feed taken during the digestion and metabolism trials is given in Table 23. The alfalfa hay fed in these trials was somewhat drier than that fed at the barn (see Table 11) and somewhat higher in protein, but the corn fed was very similar in composition to the composite samples taken at the barns.

In Table 24 the coefficients of digestibility of the nutrients in the ration, as computed in the ordinary way, have been summarized. A comparison of the average coefficients obtained with these fattening lambs and those obtained with the maintenance group consuming the

TABLE 23. — CHEMICAL COMPOSITION OF FEED CONSUMED BY THE FATTENING LAMBS DURING DIGESTION AND METABOLISM TRIALS

	Dry							Gross
Lamb No.	sub- stance	Crude protein	N-free extract	Crude fiber	Ether extract	Ash	Cal- cium	energy per
								gram

Alfalfa hay

69, 169..	perct. 92 67	perct. 18 25	perct. 41 97	perct. 22 03	perct. 2 34	perct. 8 08	perct.	sm. cals. 4172
67, 151	93 54	17 38	39 67	25 11	2 17	9 21	1 44	4215
33	93.51	17.06	43.61	22.98	2.37	7.49	1.52	4158

Corn

69, 169	88 93	8 56	73 55	2 19	3 37	1 96		3984
67, 151.. .	87 54	8 73	71 86	2 50	3 18	1 27		3935
33	87.56	8.56	72.09	2.23	3.54	1.14		3918

TABLE 24. — DIGESTION COEFFICIENTS OBTAINED WITH THE FATTENING LAMBS

Lamb No.	Dry substance	Crude protein	N-free extract	Crude fiber	Ether extract
69	perct. 77	perct. 73	perct. 89	perct. 36	perct. 66
169	75	71	88	28	65
67	76	70	89	35	62
151	76	72	89	36	62
33....	75	68	87	49	60
Average	75.8	70.8	88.4	35.4	63.0

THE MAINTENANCE AND FATTENING; OF LAMBS 51

same ration at a different level may be made by turning to Table 12. In general a higher digestibility was obtained with the fattening lambs.

The determination of the gross energy of feed and excreta in these digestion experiments permits the calculation of the metabolizable energy content of the ration, the methane excretion being estimated, according to Armsby's method for steers, from the digestible carbo- hydrates consumed. These calculations will be found in Table 25. For the fattening lambs the ration contained 2.794 therms per kilo- gram of dry matter, as compared with an average of 2.653 therms ob- tained with the maintenance lambs (Table 13). For the fattening lambs the gross energy of the ration was 62.27 percent metabolizable on the average, as compared with 59.74 percent, for the maintenance lambs.

The fattening lambs were all storing nitrogen during the collec- tion periods according to the data assembled in Table 26.

Composition of the Fat Lambs

At the end of feeding periods varying in length from 73 days to 141 days, the nine fattened lambs were slaughtered at weights of ap- proximately 90 pounds. The method of sampling was essentially the same as that followed with the maintenance lambs. For each lamb there were three samples consisting of edible flesh, bone, and offal, and for all lambs slaughtered on the same day a composite sample of wool was taken. Slight irregularities in the disposition of the bones of the head and feet, as between the bone and the offal samples, resulted thru inadvertance, but these did not affect the accuracy of the final com- putations. These irregularities are all noted in the tables. The slaugh- ter data for these lambs, the weights of samples, the results of the analysis of the samples, and the estimated composition of the total animals on the live-weight and empty-weight basis are given in Tables 27 to 30. The latter computations, as for all preceding groups of lambs, include all possible corrections for losses of moisture during slaughtering and sampling.

The fat lambs contained an average ''fill" of 11.1 percent, as com- pared with averages of 15.9 for the check lambs and 10.8 for the main- tenance lambs. On the basis of the empty weight the fat lambs con- tained an average of 24.89 percent of fat, the maintenance lambs 21.57 percent, and the check lambs 14.15 percent. The average ash percent- ages for the three groups of lambs on the same basis were 4.17, 4.09, and 4.79 respectively. The percentage of calcium in the ash of the empty carcass averaged 22.3 for the fat lambs, 24.4 for the mainten- ance lambs, and 28.5 for the check lambs. The first group of check lambs also showed a high average for this value, i.e., 27.4 percent. In the case of rats, Buckner and Peter1 obtained fairly constant percent-

'Buckner, G. D., and Peter, A. M. Jour. Biol. Chem. 54, 5. 1922.

52

BULLETIN No. 314

[August,

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1928}

THE MAINTENANCE AND FATTENING OF LAMBS

53

TABLE 26. — DAILY NITROGEN BALANCES OF THE FATTENING LAMBS DURING METABOLISM TRIALS

Lamb No.	Nitrogen of feed consumed	Nitrogen of feces	Nitrogen of urine	Total N excreted	Nitrogen balance
69...	grams 19.49	grams 5.20	grams 10.15	grams 15.35	grams +4.14
169	19.49	5.70	10.39	16.09	+3.40
67	22.72	6.90	11.17	18.07	+4.65
151	22.72	6.26	12.53	18.79	+3.93
33	18.62	5.89	9.72	15.61	+3.01

TABLE 27. — SLAUGHTER DATA FOR THE FATTENED LAMBS

(All weights in pounds)

Lamb No	67	69	151	169	54	33	90	143	49
Live weight .... Wool . .	87. 4 5 13	88.7 5.94	85.5 4 74	87.8 6.26	87.8 4.84	84.9 4.39	88.8 4.76	85.4 5.35	84.1 5.60	86.7 5 22
Blood	3.56	3.50	3.80	7.67	3.72	2.94	3.56	3.20	3.05	3 89
Skin and feet . . Caul fat .	7.44 1 75	7.00 2 69	8.55 1.85	6.35 2 34	9.19 1.39	7.56 1.65	8.13 2.18	6.65 2.20	7.00 2 90	7.54 2 11
Gut fat. . . .	.81	.81	.80	.95	.70	1.00	1.02	1.65	1.45	1.02
Contents of first three stomachs .... Contents of 4th stomach and intestines. . . . Contents of entire alimen- tary tract. . . Warm dressed	8.44 2.56 11.00 46.38	8.81 3.00 11.81 44.94	6.25 2.85 9.10 44.75	4.86 3.01 7.87 45.75	7.94 3.41 11.35 43.75	7.58 2.85 10.43 43.50	5.94 3.25 9.19 46.50	4.55 2.80 7.35 47.00	6.80 2.10 8.90 46.00	6.80 2.87 9.67 45.40
Cold dressed carcass	45.90	44.35	43.33	44.20	42.26	41.85	44.88	45.93	45.07	44.20
Percent shrinkage .... Percent "fill". . Dressing percentage. . .	1.03 12.6 52.5	1.31 13.3 50.0	3.17 10.6 50.7	3.39 9.0 50.4	3.41 12.9 48.1	3.79 12.3 49.3	3.48 10.4 50.6	2.28 8.6 53.8	2.02 10.6 53.6	2.65 11.1 51.0

TABLE 28. — WEIGHTS OF SAMPLES ANALYZED FROM THE FATTENED LAMBS

Lamb	Empty		Edible flesh			Offal	Wool
No.	weight	Lean	Fat	Total
	kgs.	grams	grams	grams	grams	grams	grams
67.	34.65	12 108	5 640	17 748	2 703'	10 989	2 327
69.	34.87	12 021	4 974	16 995	2 753'	10 747	2 694
151.	34.65	11 726	4 215	15 941	4 008 2	10 657	2 150
169.	36.24	10 738	5 682	16 420	3 88N =	11 101	2 839
54.	34.70	12 025	3 452	15 477	4 0072	10 978	2 195
33.	33.77	11 433	3 737	15 170	4 0702	10 635	1 991
90.	36.09	11 918	4 452	16 370	4 0142	10 890	2 159
143.	35.43	12 368	5 175	17 543	4 514	9 420	2 427
49.	34.11	10 584	5 885	16 469	3 825	9 910	2 540
Average..	34.95	11 658	4 801	16 459			2 369

•Exclusive of bones of head and of feet, which were put in the offal sample. 8>Jot including bones of feet, which were put in offal sample.

ages of 25 to 26 thruout the growing period. The bone samples of both the fat lambs and the maintenance lambs contained normal average percentages of calcium in the ash (37.6 and 37.5 respectively). The low ash content of the bone samples as compared with that of well- calcified bone itself is to be expected in view of the imperfect separa- tion of bone from soft tissues in the preparation of these samples.

54

BULLETIN No. 314

[August,

TABLE 29. — PERCENTAGE COMPOSITION AND ENERGY VALUE OF SAMPLES ANALYZED FROM THE FATTENED LAMBS

Lamb No.

Dry substance

Crude protein

Ether extract

Ash

Calcium

Calcium in percent of total ash

Gross energy per gram

Edible flesh samples

67 ...	51.69	13.56	36.86	1.31	.020	1 53	sm. cals. 4 196
69	51.66	13.19	35.84	1.18	.021	1.78	4 061
151 .. .	53.61	14.00	37.60	1 03	.018	1 75	4 292
169	52.14	14.56	34.23	.98	.017	1.73	4 000
54	54.19	15.56	28.60	1.07	.027	2.52	3 421
33	53.38	15.63	28 11	1 41	021	1 49	3 422
90	51.39	14.31	32.94	1.03	.020	1.94	3 794
143	48.88	15.13	33.54	.83	.021	2.53	3 968
49 ..	58.59	14.13	39.64	.73	025	3 42	4 398
Average. . . .	52.84	14.45	34.15	1.06	.021	2.08	3 950

Bone samples1

67...	70.42	19 81	22.59	24.75	9.34	37 7	3 349
69	69.66	18.86	21.79	24.26	9.22	38.0	3 391
151	57 67	17 69	18 95	19 35	7 25	37 5	2 854
169	60 79	18.52	18.87	20.32	7.75	38.1	2 904
54	58.19	18.30	16.56	21.02	7.88	37.5	2 643
33	58 09	16 51	19 00	19.35	7 24	37 4	2 830
90	59 32	18.30	17.93	20.80	7 76	37 3	2 796
143	60.69	20.41	16.23	21.79	8.20	37.6	2 742
49	60 42	21 27	16 25	21 81	8 17	37 5	2 720
Average. . . .	61.69	18.85	18.69	21.49	8.09	37.6	2 914

Offal samples2

67 ....	39 35	14 50	20.05	2.24	.519	23.2	2 759
69	38.06	14 . 56	17.13	2.39	.559	23.4	2 527
151	36 99	14 69	19 87	1 16	.061	5 26	2 576
169 .	37 94	14 13	21 98	1.14	.061	5.35	2 669
54	34.48	15.75	17.00	1.28	.076	5.94	2 327
33	35 99	15 50	19 08	1 31	102	7 79	2 563
90 ... .	38 46	14.69	20.63	1.14	.090	7.89	2 658
143	41.27	14.94	23.64	.92	.021	2.28	3 027
49	42 99	14 69	24 83	.95	.023	2 42	3 166
Average. . . .

Wool samples

67, 69. ...	89 35	60.75	9.05	11.34	.20'		4 344
151, 169, 54, 33, 90 143, 49	89.73 89.62	60.88 60.84	8.83 8.89	15.54 14.34	.203 .203		4 366 4 374

'The samples for Lambs 67 and 69 contained only the bones from the dressed carcass; those for Lambs 151, 169, 54, 33, and 90 contained in addition the bones of the head; while those for Lambs 143 and 49 contained the bones of head and feet. 2The samples for Nos. 67 and 69 contained the bones from the head and feet; those for Nos. 151, 169, 54, 33, and 90 contained the bones of the feet; while those for Nos. 143 and 49 contained only the viscera and other waste. 3The average calcium content of a composite sample of wool from all fat sheep.

In Table 30, the nine fat lambs are arranged in the order of their slaughter. No progressive differences in composition are evident, so that the data obtained do not indicate that the rapid gains are ap- preciably different in composition from the slow gains.

Composition of the Gains in Weight

On the assumption that the fat lambs at their initial weights possessed the same composition on the live-weight basis as the second

IMS]

THE MAINTENANCE AND FATTENING OF LAMBS

55

TABLE 30. — PERCENTAGE COMPOSITION AND GROSS ENERGY CONTENT OF THE FATTENED LAMBS1

						Calcium	Gross
Lamb No.	Dry substance	Crude protein	Ether extract	Ash	Calcium	in percent of total	energy per gram
						ash

On basis of live weight

67...	44.10	15.01	24.14	3.56	.80		sm. cats. 2 492
69	42 74	14 82	21 82	3 56	80		2 914
151	43 14	15 00	23 37	3 61	78		3 010
169	44.43	16.10	22 47	3.82	.79		2 988
54	41.34	15.58	17.96	3.74	.84		2 476
33	41 76	15 33	18 82	3 77	81		2 582
90	42 02	14.89	21 24	3 61	.82		2 775
143	44.84	16.65	23.37	4.03	.98		3 125
49	48 49	16 10	25 78	3 70	85		3 285
Average. . . .	43.65	15.50	22.10	3.71	.83		2 849

On basis of empty weight

67 .	50 45	17 17	27 61	4 07	92	22 6	2 851
69	49 31	17 10	25 17	4.10	.93	22 7	3 361
151	48.28	16 78	26 15	4.04	.87	21.6	3 368
169	48 80	17 68	24 96	4 19	87	20 7	3 284
.~)4 .	47 48	17 88	20 61	4 29	96	21 9	2 844
33	47.61	17 48	21 45	4.29	.93	21.7	2 943
90	46.88	16.60	23.69	4.03	.91	22.2	3 095
143	49 06	18 23	25 57	4 41	1 07	24 3	3 419
49 . ...	54.22	18 01	28 84	4 14	.95	22.9	3 674
Average. . . .	49.12	17.43	24.89	4.17	.94	22.3	3 205

'Xos. 67 and 69 were killed after 82 days of feeding; 151, 169, 54, 33, and 90 after 97 days; 143 after 131 days; and 49 after 141 days of feeding.

group of check lambs (Table 9), it is possible to compute the compo- sition of the gains put on during the fattening period. The results of such a calculation, expressed as percentages of the estimated increase in empty weight, are given in Table 31. The great variation among the individual estimates is due not only to the differences in the actual composition of gains but also to the not inconsiderable error in the method of estimation, according to which all of the lambs are assumed to possess the same initial composition.

The average gain in empty weight from about 65 to about 90 pounds contained 75.1 percent of dry matter, 11.9 percent of crude

TABLE 31. — ESTIMATED PERCENTAGE COMPOSITION AND ENERGY VALUE OF GAINS IN EMPTY WEIGHT PUT ON BY THE FATTENED LAMBS

Lamb Xo.	Dry substance	Crude protein	Ether extract	Ash	Gross energy per pound
67	79.8	10 9	63 4	2 1	therms 3 11
69	81.8	9.2	61.2	1 8	3 03
151	73 3	9 1	59 9	2 0	2 83
169	73.7	12.9	53 7	2 6	2 62
54	68.8	13.5	37.6	3.0	1 89
33	70 3	11.8	41 5	2 9	2 08
90	63.3	10.2	44.6	2 3	2 15
143	71 5	15 3	52 2	3 6	2 68
49	93.3	14.0	67.8	2 5	3.27
Average	75.1	11.9	53.6	2.5	2.63

56

BULLETIN No. 314

[August,

protein, 53.6 percent of fat, and 2.5 percent of ash. The computations for calcium indicated no increase in the store of this mineral. The nine lambs contained an average of 327 grams of calcium at slaughter and were estimated to have contained an average of 344 grams initially. It seems improbable that no calcium was stored during the fattening period. A slight storage, however, may have been obscured by the possible error in the estimation of the initial calcium composition of the lambs.

Each pound of gain in empty weight contained on the average 2.63 therms of gross energy. This value is less than the average value of 3.25 therms given by Armsby to the energy content of a pound of gain by fattening animals, but is almost identical with the value re- ported by Wood1 for two sheep gaining from an average of 87 to one of 124 pounds in body weight, i.e., 2.64 therms. In Bulletin 283 from this Station the average energy value of a pound of gain in empty weight from 87 to 117 pounds was found to equal 2.58 therms. Ap- parently the weight increase of sheep is remarkably constant in energy content, largely because it is fairly constant in fat content. In this experiment the average fat content was 53.6 percent; in the preceding experiment at this Station it was found to be 47.7 percent, and in the experiment of Wood it averaged 50.7 percent (on the increase in live weight). The crude protein percentages were not so constant, averaging 11.9, 13.2, and 17.6 respectively for the three experiments.

Distribution of Added Nutrients in the Carcasses

It is of interest to compute the distribution of the added nutrients among the dressed carcass, the offal, and the wool. Such calculations are complicated somewhat by the different methods of making up the samples for the check and fat lambs, but satisfactory results may be obtained on the assumption that the head and feet bones possessed the same chemical composition as the bones of the dressed carcass.

TABLE 32. — PERCENTAGE DISTRIBUTION OF GAINS IN CHEMICAL CONSTITUENTS OF THE FAT LAMBS AMONG DRESSED CARCASS, WOOL, AND OFFAL

	Dry substance	Crude protein	Fat	Ash	Gross energy
Dressed carcass. . . Wool	66.7 s s	54.8 26 3	71.4 2 1	15.3 64 9	69.6 5 2
Offal	24 . 5	18.9	26 o	19 8	25 2
Total	100.0	100.0	100.0	100.0	100.0

The weights of head and feet bones were obtained for the fat lambs, so that the composition of the dressed carcass can be approximated. The results obtained on this question are assembled in Table 32.

'Wood, T. B. Jour. Min. Agr. [Gr. Brit.] 34, 295. July, 1927.

THE MAINTENANCE AND FATTENING OF LAMBS 57

With the exception of the added mineral matter the dressed car- cass received most of the nutrient material added to the bodies of the lambs during their fattening period. An average of 66.7 percent of the added dry matter, 54.8 percent of the added protein, 71.4 percent of the added fat, 15.3 percent of the added mineral matter, and 69.6 per- cent of the added gross energy were found in the dressed carcasses of these lambs. The added wool contained about two-thirds of the added mineral matter and about one-fourth of the added protein but very little of the added energy. The mineral matter found in the wool con- tained only a trace of calcium and probably consisted of dirt to a large extent. The failure of these lambs to increase in calcium content altho increasing in mineral content is thus partially explained.

The main difference in the disposition of added nutrients in the carcass between these young lambs and the more mature sheep of the preceding experiment1 relates to the protein. In the former experiment 60 percent of the added protein was found in the wool, the growth of the carcass being largely completed. In the present experiment less than 20 percent of the added protein was found in the wool, the dressed carcass alone containing about 55 percent and the offal parts over 25 percent.

With the more mature sheep, wool growth accounted for greater percentages of all added nutrients than with the growing lamb. It was also formed at a much more rapid rate, being equivalent to a daily growth of .149 pound of protein and 566 calories of gross energy per day per 1,000 pounds live weight. In the experiment on growing lambs the daily growth of wool contained an average of only .086 pound of protein and 377 calories per 1.000 pounds live weight.

Utilization of Feed Energy in Fattening

The relation between the feed energy consumed by the fattening lambs and their average daily retention of energy is of interest in throwing light upon the efficiency of utilization of energy by sheep. The calculations given in Table 33 are concerned with this relation. The average energy content of the lambs at slaughter was 114.8 therms. Their initial content, as computed from the initial weights and the average energy content of the second group of check lambs per unit of live weight, averaged 59.4 therms. The gain in energy therefore averaged 55.4 therms, or 568 calories, daily. The average daily intake of metabolizable energy was 2,427 calories, of which 1.254 calories were estimated to have been used for maintenance. This estimate is based upon the average weight of the lambs during the feeding period and the average metabolizable energy requirements for maintenance as previously determined, i.e., 1,637 calories per 100 pounds live weight.

'111. Agr. Exp. Sta. Bui. 283, 243, Table 25.

58

BULLETIN Xo. 314

[August,

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1928] THE MAINTENANCE AND FATTENING OF LAMBS 59

the direct ratio of weights being used. Hence, according to these fig- ures 1,173 calories of metabolizable energy may be considered as avail- able for production. The production secured averaged 568 calories daily, or an average of 48.5 percent of the metabolizable energy avail- able.

As previously mentioned (page 45), experimental work with steers indicates a percentage availability of metabolizable energy of 53 to 55 for a ration of equal parts of corn and alfalfa hay. The results of this experiment point, therefore, to a somewhat less efficiency on the part of the sheep as compared with the steer in the utilization of metaboliz- able energy. For alfalfa hay alone results have been reported previ- ously for sheep (Bulletin 283) that are equal to several reported by Armsby for steers but inferior to some of the later results.

SUMMARY

The digestibility of a ration consisting of equal parts by weight of alfalfa hay and shelled corn was investigated at two levels of feed- ing, one representing but little more than a maintenance ration (eight lambs) and the other representing full feed (five lambs). The coeffi- cients of digestibility at the higher level were generally greater than those at the lower, altho the differences were not large. At the higher level 62.3 percent of the gross energy of the ration was found to be metabolizable, while at the lower only 59.7 percent was metabolizable. The metabolizable energy of the ration per kilogram of dry matter was 2.794 therms at the higher level, and 2.653 therms at the lower. For steers the gross energy in a ration of equal parts of corn and alfalfa hay has been found to be 60 to 61 percent metabolizable.

In feeding tests upon eight lambs averaging 69 pounds in weight, the maintenance requirements in terms of pounds of feed and of metabolizable energy per 100 pounds of weight have been determined for a ration containing equal parts of alfalfa hay and corn. The data of feed consumption, feed analyses, and digestion and metabolism trials have been supplemented by carcass analyses of check lambs and of the maintenance lambs at the end of their feeding period, in order to correct for a storage of energy in the body. It was found that 1.53 pounds of feed and 1,637 calories of metabolizable energy were required per 100 pounds weight for the maintenance of energy equi- librium. These values may be compared with those determined in a previous experiment for a ration of alfalfa hay alone, i.e., 2.29 pounds and 1,820 calories of metabolizable energy.

Nine lambs were used in a fattening experiment to determine the efficiency in the use of metabolizable energy for production. These lambs were fattened from about 65 pounds in weight to about 90

60 BULLETIN No. 314

pounds, at which weight they were slaughtered and analyzed. Di- gestion and metabolism experiments were run upon five of these lambs.

Altho the daily rate of gain varied from .18 to .36 pound, no relation could be detected between the rate of gain and the composition of the carcass. On the average the fat content of the empty carcass increased from 14.15 percent, as determined by the analysis of eight check lambs at approximately the initial weight, to 24.89 percent.

The average gain in empty weight was calculated to possess the following composition: 75.1 percent of dry matter, 11.9 percent of pro- tein, 53.6 percent of fat, and 2.5 percent of ash. Its gross energy value was 2.63 therms per pound.

Altho the ash content of the lambs increased during fattening, no increase in the calcium content could be demonstrated. A small in- crease might well have been obscured by the possible error in the slaughter experiment. The absence of any indication of a large in- crease in calcium was due to two factors. In the first place, 65 percent of the increase in ash occurred in the wool, and largely represented outside contamination. Again, the percentage of calcium in the ash of the entire carcass decreased from 27.4 to 28.5 in the check lambs to 22.3 in the fattened lambs, the maintenance lambs showing an average of 24.4.

The gains in nutrients by the fat lambs were largely added to the dressed carcass. Thus 66.7 percent of the dry matter of the gains, 54.8 percent of the protein, 71.4 percent of the fat, and 69.6 percent of the gross energy gained were deposited in the dressed carcass. The wool growth accounted for 8.8 percent of the dry matter gained, 26.3 percent of the protein. 2.1 percent of the fat, and 5.2 percent of the energy.

The daily wool growth of these young lambs contained per 1,000 pounds live weight .086 pound of protein and 377 calories. These values are only about 60 percent as large as those obtained with larger and older sheep in a previous experiment.

The daily gain of energy by the fattening lambs averaged 568 calories. The average intake of metabolizable energy was 2,427 cal- ories daily, of which 1,254 calories were estimated to have been re- quired for maintenance. The difference, 1,173 calories, may therefore be compared with the energy storage to determine the efficiency of utilization of the metabolizable energy consumed in excess of the maintenance requirements. The daily storage of 568 calories is 48.5 percent of the metabolizable energy apparently available for this pur- pose. We may say, therefore, that between a maintenance level of feeding and the full- feed level attained by the fattening lambs, the metabolizable energy of the ration of alfalfa hay and corn was 48.5 percent net available. For steers a utilization of 53 to 55 percent would be expected for this ration.

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